Methods of Retrofitting Injection Molding Machines

ABSTRACT

An injection molding machine that uses a mold and a native controller to operate according to an original mold cycle to mold plastic objects is retrofitted with a retrofit controller; the retrofitted machine uses the mold and the retrofit controller to operate according to a retrofit mold cycle to mold plastic objects.

FIELD OF THE INVENTION

The present application generally relates to injection molding, andspecifically relates to injection molding machines that are retrofittedwith a controller having a retrofit mold cycle.

BACKGROUND OF THE INVENTION

Injection molding machines are commonly used to mold plastic objects. Aninjection molding machine molds plastic objects by repeatedly performinga mold cycle. During each mold cycle, the machine injects molten plasticinto a mold, cools the plastic, opens the mold, ejects the moldedobject, closes the mold, and recovers for the next cycle. Variousinjection molding machines include variations of this mold cycle, asknown in the art. A controller, which is programmed with the mold cycle,controls the machine according to the mold cycle.

Injection molds are designed to mold particular objects from particularplastics at particular pressures. Injection molding machines aredesigned to accept a range of mold sizes and to inject plastic within arange of injection pressures. A molding machine and its mold can bedesigned to last for many mold cycles.

It can be challenging to make changes to an injection molding machine.Since a molded object is planned for a particular end use, it is usuallynot feasible to significantly change its plastic material. Since a moldis manufactured with particular geometries shaped in metal, it isusually not possible to significantly change its configuration. Andsince an injection molding machine is designed and built as a complete,integrated unit, it is usually impractical to change its set-up.

Thus, many molding machines operate with substantially the samematerial, mold, and mold cycle, for the life of the mold—sometimes manyyears. On the one hand, operating over a long life allows this equipmentto pay back its large capital expense. On the other hand, operating overa long life without significant improvements means that anyinefficiencies in the mold cycle accumulate more costs over time.

SUMMARY OF THE INVENTION

However, embodiments of the present disclosure can be used to improvethe operation of a molding machine by changing its original mold cycleto a retrofit mold cycle. The original mold cycle is the mold cycle usedon an injection molding machine that has not yet been retrofitted withthe addition of a retrofit controller to the machine. The retrofit moldcycle is the mold cycle that differs from the original mold cycle, andis used on an injection molding machine that has been retrofitted withthe addition of a retrofit controller to the machine.

A retrofit mold cycle can allow an injection molding machine to uselower injection pressures, when compared with the original mold cycle.Operating at lower pressures uses less energy, reduces stress onmechanical components, and increases the safety factor for the machine.The machine can use less energy at lower pressures since its injectionunit does not need to perform as much work. The reduced stress canlengthen the life of mechanical components and decrease the possibilityof their failure. The machine can operate at an increased safety factor,since there will be a relatively greater difference between itsoperating pressures and the maximum rated pressure for the machine.

A retrofit mold cycle can also allow an injection molding machine to usemore constant injection pressures, when compared with the original moldcycle. Operating at more constant pressures provides better melt flowthrough the mold cavity and better contact between the molten plasticand the surface of the mold cavity. Better melt flow can lead tosmoother and more consistent filling, which improves the quality of themolded object. Better contact can lead to better heat-transfer betweenthe molten plastic and the mold. Better heat transfer can ensure thatplastic remains molten throughout the filling (avoiding ‘freeze-off’problems). Better heat transfer can also provide faster cooling. Fastercooling can lead to faster mold cycle times and thus, greater throughputfor the machine.

In various embodiments, a retrofitted molding machine can use a retrofitcontroller to mold according to a retrofit mold cycle can that has anaverage retrofit cycle time (averaged over ten consecutive cycles ofmaking production versions of molded part(s)), which is the same as oreven shorter (i.e. faster) than an average original cycle time (alsoaveraged over ten consecutive cycles of making production versions ofmolded part(s)) for an original mold cycle previously used. For example,depending on the particular application, a retrofit average cycle timecan be shorter by 5-50%, or any integer value for percentage in thatrange, or any range formed by any of those integer values, such as from5-40%, or from 10-30%, or from 15-25%.

Further, in various embodiments, even after an injection molding machineis retrofitted with a retrofit controller, the machine may continue topartially use the native controller, with the native controllerassisting in controlling the machine according to a retrofit mold cycle.In particular, the retrofit controller can begin to control some or allof the plastic injecting in the retrofit mold cycle, while the nativecontroller can continue to control some or all of the other functions inthe retrofit mold cycle. This approach offers some advantages overcompletely replacing a native controller with a retrofit controller.

A first advantage of this retrofitting approach is reducing complexityand cost. Since the native controller can be left to control functionssuch as cooling the plastic, opening the mold, ejecting the moldedobject, closing the mold, and recovering the machine conditions for anew cycle, the retrofit controller does not require logic, commands,and/or executable program instructions to perform these functions. Thismakes the retrofit controller simpler and cheaper to design and build.And, since the native controller continues to control these functions,some or all of the inputs and/or outputs related to these functions donot need to be transferred to the retrofit controller. This makes theretrofitting process faster and more straightforward, requiring lesslabor and less downtime for the machine.

A second advantage of this retrofitting approach is targetingsignificant improvements. While changes to the other functions (cooling,opening, ejecting, closing, recovery, etc.) can affect the mold cycle,changes to the plastic injecting can provide much more significantimprovements to the mold cycle (as explained above and herein). So theplastic injecting is the key portion of the mold cycle, for makingimprovements. Since the retrofit controller is specifically designed tocontrol the plastic injecting in a new and improved way, the retrofitcontroller provides a targeted benefit to the retrofitted injectionmolding machine, when it is controlled according to the retrofit moldcycle. Additionally, since the retrofit controller does not need tocontrol the other functions, the retrofit controller is able to achievefaster processing for its control of the plastic injecting.

A third advantage of this retrofitting approach is continuing aspects ofthe original design for the molding machine. Since an injection moldingmachine is designed and built as a complete, integrated unit, the nativecontroller includes logic, commands, and/or executable programinstructions that were matched to known specifications of the machine'scomponents. The logic, commands, and/or executable program instructionswere also designed to be part of an overall safety scheme for themachine. By continuing to use the native controller to at leastpartially control the retrofit mold cycle, there is a reduced risk thatthe retrofitted machine will work in an incorrect or unsafe manner.Further, by adding a retrofit controller while retaining the nativecontroller, the machine manufacturer's warranty may continue, withoutbeing voided.

A fourth advantage of this retrofitting approach is leveraging existingfamiliarity with the native controller and the molding machine. Aninjection molding machine includes a user interface, which allows itsusers to start, monitor, and stop the machine. An injection moldingmachine also includes various machine configurations, which are commonto its manufacturer, are explained in its original technicaldocumentation (e.g. manuals), and are likely known to technicians whomaintain and repair the machine. By continuing to use the nativecontroller to at least partially control the retrofit mold cycle, it ispossible to maintain most (or even all) of the original user interfaceas well as many of the original machine configurations. As a result,operators and technicians may need little (or even no) additionaltraining, to competently use and service the retrofitted machine.

A fifth advantage of this retrofitting approach is the ability to easilydisable the retrofit controller, if needed. A retrofitted injectionmolding machine can include a disable switch, which can allow a user ofthe retrofitted injection molding machine to select a mode of injectionmolding that disables the retrofit controller, such that the machine andthe native controller mold production versions of the plastic objectaccording to the original mold cycle. The disable function can be usefulfor isolating the retrofit controller from the rest of the moldingmachine for trouble-shooting purposes. The disable function can alsoenable a user to switch back to an original mold cycle for specificinstances where running the original mold cycle is required.

It is believed that the embodiments of retrofitting in the presentdisclosure can be used with various kinds of injection moldingapplications for various molded objects. However, it is expected thatthe embodiments of retrofitting in the present disclosure offerparticular advantages to molded objects with small Nominal WallThickness (NWT), molded objects with large Length-over-Thickness (L/T)ratios, and molded objects that exhibit shear-thinning behavior. As anexample, it is expected that the embodiments of retrofitting in thepresent disclosure offer particular advantages to molded objects withNWT of 0.1-10 millimeters, or any value in increments of 0.1 millimeterswithin that range, or any range formed by any of these values, such as0.5-8 millimeters, 1.0-5 millimeters, 1.5-3 millimeters, etc. As anotherexample, it is expected that the embodiments of retrofitting in thepresent disclosure offer particular advantages to molded objects withL/T ratios of 50-500, or any integer value within that range, or anyrange formed by any of these values, such as 100-500, 150-500, 200-500,250-500, 100-300, 100-250, 100-200, 100-150, etc.

In various embodiments, an injection molding machine can include aninjection unit, a nozzle, and a mold, in fluid communication with eachother, as known in the art. The injection unit can be any kind ofinjection unit, which uses pressure to inject molten plastic through thenozzle and into the mold. As examples, an injection unit can behydraulically driven, mechanically driven, electrically driven, orcombinations of these, or any other kind of injection unit, as describedherein, or as known in the art. The mold can be any kind of mold withone or more cavities to mold one or more plastic objects. (Althoughexplanations and examples herein may refer to a single molded plasticobject, this is for convenience and should not be construed as alimitation; the present disclosure contemplates that any embodimentdisclosed herein can be used with a mold having any number of cavities.)Any of the components of the injection molding machine, such as theinjection unit, can have a maximum rated injection pressure, with therating provided by the manufacturer. For example, an injection moldingmachine can include an injection unit having a maximum rated injectionpressure from 15,000 psi (103.42 MPa) to 60,000 psi (413.69 MPa) or anyinteger value for psi in that range, or any range formed by any of thoseinteger values, such as from 20,000 psi (137.90 MPa) to 50,000 psi(344.74 MPa) or from 25,000 psi (172.37 MPa) to 40,000 psi (275.79 MPa).

The molding machine can include a native controller. The nativecontroller can be any kind of controller, such as an electro-mechanicalcontroller, a circuit board, a programmable logic controller, anindustrial computer, or any other kind of controller, as describedherein, or as known in the art. The native controller can be set,configured, and/or programmed to partially or fully control some or allparts of the injection molding machine, as described herein, or as knownin the art. The native controller can be set, configured, and/orprogrammed with logic, commands, and/or executable program instructionsaccording to any embodiment disclosed herein, or as known in the art.

The native controller can be physically positioned in various ways, withrespect to the injection molding machine. As examples, the nativecontroller can be integral with the machine, the native controller canbe contained in an enclosure that is mounted on the machine, the nativecontroller can be contained in a separate enclosure that is positionedadjacent or proximate to the machine, or the native controller can bepositioned remote from the machine. In some embodiments, the nativecontroller can partially or fully control functions of the machine bywired signal communication; in other embodiments the native controllercan partially or fully control functions of the machine by wirelesssignal communication, as known in the art.

The native controller can be set, configured, and/or programmed topartially or fully control injection pressures of the machine. Thenative controller can control injection pressures in any way describedherein or known in the art. As an example, the native controller cancontrol injection pressures by controlling rates of injection by theinjection unit. As another example, the native controller can controlinjection pressures by controlling rates of melt flow through thenozzle.

The native controller can be set, configured, and/or programmed withlogic, commands, and/or executable program instructions correspondingwith an original mold cycle. The native controller can use, perform,and/or execute such logic, commands, and/or instructions, to control theinjection molding machine to cause the machine to mold plastic objectsaccording to the original mold cycle.

As an example, an injection molding machine can use an original moldcycle to inject plastic according to a conventional mold cycle, whichincludes the following portions: initial injecting, filling, packing,and holding. An original mold cycle has a maximum original injectionpressure, which is the highest injection pressure reached during thecycle. Throughout the present disclosure all injection pressures aremeasured in the nozzle, unless stated otherwise.

In various conventional embodiments, an original mold cycle can have amaximum original injection pressure that is 65-100% of the maximum ratedinjection pressure for the injection unit (or for the molding machine),or any integer value for percentage in that range, or any range formedby any of those integer values, such as 70-100%, 75-100%, or 80-100% ofthe maximum rated injection pressure. In various conventionalembodiments, an original mold cycle can have a maximum originalinjection pressure from 20,000 psi (137.90 MPa) to 60,000 psi (413.69MPa) or any integer value for psi in that range, or any range formed byany of those integer values, such as from 25,000 psi (172.37 MPa) to50,000 psi (344.74 MPa) or from 30,000 psi (206.84 MPa) to 40,000 psi(275.79 MPa).

In various conventional embodiments, an original mold cycle can haveinjection pressures that vary significantly over the course of the moldcycle, or vary within part, parts, or all of any particular portion ofthe mold cycle. As examples, for at least part of a filling portion ofan original mold cycle, an injection pressure of a machine can vary by10-60%, by 20-60%, or even by 30-60%, with respect to an original targetinjection pressure, or a reference value for injection pressure, forpart, parts, substantially all, or all of the filling portion. Suchvariations can occur within 50-100% of the filling portion, or anyinteger value for percentage in that range, or any range formed by anyof those integer values, such as 60-100%, 70-100%, or 80-100% of thefilling portion. Such periods of variation can occur at the beginning ofthe filling portion, can occur at the end of the filling portion, and/orcan be centered on the middle of the filling portion.

An injection molding machine can have a native controller programmedwith a maximum programmed original safe pressure setting that is 80-120%of the maximum rated injection pressure for the injection unit (or forthe molding machine), or any integer value for percentage in that range,or any range formed by any of those integer values, such as 90-110%,90-100%, or 95-105% of the maximum rated injection pressure. The nativecontroller can be programmed to stop the injection unit if an injectionpressure of the injection molding machine exceeds the maximum programmedoriginal safe pressure setting.

An injection molding machine can also have an original pressure reliefmechanism with a maximum original safe pressure setting that is 80-120%of the maximum rated injection pressure for the injection unit (or forthe molding machine), or any integer value for percentage in that range,or any range formed by any of those integer values, such as 90-110%,90-100%, or 95-105% of the maximum rated injection pressure. Thepressure relief mechanism can be set to relieve pressure in theinjection molding machine if an injection pressure of the machineexceeds the maximum original safe pressure setting.

An injection molding machine can be retrofitted by adding a retrofitcontroller to the machine, as described herein. The machine that isretrofitted can be the same machine in which a mold was run according toan original mold cycle, or the machine being retrofitted may be adifferent molding machine having the same configuration as the machinethat ran the original mold cycle. Any of the functions and benefits ofretrofitting described herein can be obtained by using the same machine(or a machine of the same configuration).

The retrofitted machine can run the retrofit mold cycle using the samemold that was used to run the original mold cycle, or the retrofittedmachine may use a different mold having the same configuration as themold used with the original mold cycle. Any of the functions andbenefits of retrofitting described herein can be obtained by using thesame mold (or a mold of the same configuration).

The retrofitted machine can run the retrofit mold cycle using the sameplastic material that was used in the original mold cycle, or theretrofitted machine may use a different plastic material that isessentially the same, or that has material properties (such as Melt FlowIndex), which are the same, or substantially the same.

The retrofit controller can be any kind of controller, such as anelectro-mechanical controller, a circuit board, a programmable logiccontroller, an industrial computer, or any other kind of controller, asdescribed herein, or as known in the art. The retrofit controller can beset, configured, and/or programmed to partially or fully control some orall parts of the injection molding machine, as described herein, or asknown in the art. The retrofit controller can be set, configured, and/orprogrammed with logic, commands, and/or executable program instructionsaccording to any embodiment disclosed herein, or as known in the art.

In some embodiments of retrofitting, the retrofit controller can replacethe native controller and replace all of its functions. In otherembodiments of retrofitting, the retrofit controller can be added as anaddition to the native controller and replace less than all of itsfunctions. In alternative embodiments, a native controller can bereconfigured to become a retrofit controller, as described herein.

In any of the prior embodiments, the retrofitting can includeestablishing signal communication between the retrofit controller andthe injection molding machine. This establishing can include connectingone or more outputs from sensors (e.g. pressure sensors, temperaturesensors, positions sensors, etc.) on the machine, to one or more inputsof the retrofit controller. This connecting can include disconnectingone or more of the existing sensor outputs from the native controllerand connecting those existing sensor outputs to the retrofit controller,or adding more outputs to one or more of the existing sensors andconnecting those added outputs to the retrofit controller, orcombinations of these. This connecting can involve one or more existingsensors already in place on the molding machine, or moving one or moreexisting sensors to new locations on the molding machine, or installingone or more new sensors on the molding machine, or combinations ofthese.

The retrofitting can use any kind of (existing or new) sensor describedherein or known in the art. The signal communication can be any kind ofsignal (e.g. hydraulic, pneumatic, mechanical, analog electrical,digital electrical, optical, etc.) described herein or known in the art.

In any of the prior embodiments, the retrofitting can includeestablishing signal communication between the retrofit controller andthe native controller. This establishing can include connecting one ormore outputs of the native controller to inputs of the retrofitcontroller, connecting one or more outputs of the retrofit controller toinputs of the native controller, or otherwise sharing signals, data,and/or information between the native controller and the retrofitcontroller in any way described herein or known in the art, orcombinations of these.

The retrofit controller can be physically positioned in various ways,with respect to the injection molding machine. As examples, the retrofitcontroller can be integral with the machine, the retrofit controller canbe contained in an enclosure that is mounted on the machine, theretrofit controller can be contained in a separate enclosure that ispositioned adjacent or proximate to the machine, or the retrofitcontroller can be positioned remote from the machine. In someembodiments, the retrofit controller can partially or fully controlfunctions of the machine by wired signal communication; in otherembodiments the retrofit controller can partially or fully controlfunctions of the machine by wireless signal communication, as known inthe art.

The retrofit controller can be set, configured, and/or programmed topartially or fully control injection pressures of the machine. Theretrofit controller can control injection pressures in any way describedherein or known in the art. As an example, the retrofit controller cancontrol injection pressures by controlling rates of injection by theinjection unit. As another example, the retrofit controller can controlinjection pressures by controlling rates of melt flow through thenozzle.

The retrofit controller can be set, configured, and/or programmed withlogic, commands, and/or executable program instructions correspondingwith any portion, or any multiple portions, or all of a retrofit moldcycle. The retrofit controller can use, perform, and/or execute suchlogic, commands and/or instructions, to control the injection moldingmachine to cause the machine to mold plastic objects according to theretrofit mold cycle.

A retrofitted injection molding machine can inject plastic according toa retrofit mold cycle, which includes the following portions: initialinjecting, filling, and decreasing pressure. A retrofit mold cycle canhave a maximum retrofit injection pressure, which is the highestinjection pressure reached during the cycle.

In various embodiments, a retrofit mold cycle can have a maximumretrofit injection pressure that is 10-60% of the maximum originalinjection pressure of the original mold cycle, or any integer value forpercentage in that range, or any range formed by any of those integervalues, such as 20-60%, 30-60%, or 40-60% of the maximum originalinjection pressure.

In such embodiments, wherein a retrofit mold cycle has one or morereduced pressures, when compared with an original mold cycle, suchreductions can be achieved even when using the same (or similar)injection molding machine, the same (or similar) mold, and/or the same(or similar) plastic material, as was used with the original mold cycle.

Also, in embodiments wherein a retrofit mold cycle has one or morereduced pressures, when compared with an original mold cycle, suchreductions can be achieved even when using a machine temperature profile(i.e. the overall configuration of heating elements, and their processsettings for the molding machine) that is the same or substantially thesame.

Alternatively, in embodiments wherein a retrofit mold cycle has one ormore reduced pressures, when compared with an original mold cycle, suchreductions can allow for temperature reductions in the machine'stemperature profile (as used herein, an injection molding machine'stemperature profile refers to the average of all of the temperatureset-points for all of the heaters used to heat the plastic beingprocessed by the injection molding machine); while such reductions mightprovide an otherwise unacceptable increase in melt pressures in themachine, reducing the injection pressure can allow such temperaturereductions to be realized.

In various embodiments, a retrofit mold cycle can use a machinetemperature profile that is 5-50° C. less than a machine temperatureprofile of an original mold cycle, or less by any integer value fordegrees Celsius between 5 and 50, or less by any range formed by any ofthose integer values, such as 5-40° C. less, 5-30° C. less, 5-20° C.less, 5-10° C. less, 10-50° C. less, 20-50° C. less, 30-50° C. less,40-50° C. less, 10-40° C. less, 20-30° C. less, etc.

Such reduced machine temperature profiles can be obtained with respectto machine temperature profile measurements taken at various times. As afirst example, any of the reduced machine temperature profiles describedabove can be obtained by comparing an average original mold cyclemachine temperature profile (which is the average machine temperatureprofile over the course of an original mold cycle) with an averageretrofit mold cycle machine temperature profile (which is the averagemachine temperature profile over the course of a retrofit mold cycle).As a second example, any of the reduced machine temperature profilesdescribed above can be obtained by comparing an average original fillingportion machine temperature profiles (which is the average machinetemperature profile over the course of a filling portion of an originalmold cycle) with an average retrofit filling portion machine temperatureprofile (which is the average machine temperature profile over a fillingportion of a retrofit mold cycle). As a third example, any of themachine temperature profiles described above can be obtained bycomparing a machine temperature profile at the beginning of a fillingportion of an original mold cycle to a machine temperature profile atthe beginning of a filling portion of a retrofit mold cycle. As a fourthexample, any of the machine temperature profiles described above can beobtained by comparing a machine temperature profile at the end of afilling portion of an original mold cycle to a machine temperatureprofile at the end of a filling portion of a retrofit mold cycle.

When a machine's temperature profile is reduced as part of a retrofitmold cycle, the molten plastic can experience a reduced temperature,when compared to the temperature of the molten plastic during anoriginal mold cycle. Throughout the present disclosure all temperaturesof the molten plastic are measured in the nozzle, unless statedotherwise.

A retrofit mold cycle can cause molten plastic in an injection moldingmachine to experience a reduced temperature that is 5-50° C. less than atemperature of molten plastic in the machine during an original moldcycle; the reduced temperature can also be less by any integer value fordegrees Celsius between 5 and 50, or less by any range formed by any ofthose integer values, such as 5-40° C. less, 5-30° C. less, 5-20° C.less, 5-10° C. less, 10-50° C. less, 20-50° C. less, 30-50° C. less,40-50° C. less, 10-40° C. less, 20-30° C. less, etc.

Such reduced melt temperatures can be obtained with respect totemperature measurements taken at various times. As a first example, anyof the reduced melt temperatures described above can be obtained bycomparing a maximum original melt temperature (which is the highest melttemperature reached during an original mold cycle) with a maximumretrofit melt pressure (which is the highest melt temperature reachedduring a retrofit mold cycle). As a second example, any of the reducedmelt temperatures described above can be obtained by comparing anaverage original mold cycle melt temperature (which is the average melttemperature of the molten plastic over the course of an original moldcycle) with an average retrofit mold cycle melt temperature (which isthe average melt temperature of the molten plastic over the course of aretrofit mold cycle). As a third example, any of the reduced melttemperatures described above can be obtained by comparing an averageoriginal filling portion melt temperature (which is the average melttemperature of the molten plastic over the course of a filling portionof an original mold cycle) with an average retrofit filling portion melttemperature (which is the average melt temperature of the molten plasticover a filling portion of a retrofit mold cycle). As a fourth example,any of the reduced melt temperatures described above can be obtained bycomparing a melt temperature at the beginning of a filling portion of anoriginal mold cycle to a melt temperature at the beginning of a fillingportion of a retrofit mold cycle. As a fifth example, any of the reducedmelt temperatures described above can be obtained by comparing a melttemperature at the end of a filling portion of an original mold cycle toa melt temperature at the end of a filling portion of a retrofit moldcycle.

In such embodiments, wherein a retrofit mold cycle causes the moltenplastic to experience one or more reduced temperatures, when comparedwith an original mold cycle, such reductions can be achieved even whenusing a plastic material that is the same, or essentially the same, orhaving material properties (such as Melt Flow Index), which are thesame, or substantially the same.

A retrofit controller can be programmed with a retrofit target injectionpressure for a filling portion of a retrofit mold cycle. The retrofittarget injection pressure for the filling portion can be estimated,calculated, or empirically determined. For example, a retrofit targetinjection pressure can be empirically determined by iteratively testinga molding machine with different injection pressures. A startingpressure for this testing can be a maximum original injection pressurefor an original mold cycle or an original target injection pressure fora filling portion of the original mold cycle. From the startingpressure, the testing can include operating the molding machine atprogressively lower injection pressures, and verifying a quality ofmolded objects made by the machine at each lower pressure. In variousembodiments, a bracketing approach can be used, to determine arelatively lower retrofit target injection pressure, at which themolding machine can still make a molded object of good quality.

In any embodiment disclosed herein, a retrofit mold cycle can haveinjection pressures that vary somewhat over the course of the moldcycle, or vary within part, parts, or all of any particular portion ofthe mold cycle, but are still substantially constant. As used herein, aninjection pressure is considered to be “substantially constant” when theinjection pressure varies up or down by less than 30% with respect to atarget injection pressure or a reference value for injection pressure.As examples, for at least part of a filling portion of an original moldcycle, an injection pressure of a machine can be substantially constantand vary by less than 30%, by less than 20%, by less than 10%, or evenby less than 5%, with respect to a retrofit target injection pressure,or a reference value for injection pressure, for the filling portion.Such limits on variation can be in effect within 50-100% of the fillingportion, or any integer value for percentage in that range, or any rangeformed by any of those integer values, such as 60-100%, 70-100%,80-100%, or 90-100% of the filling portion. Such limitations on pressurevariation can begin at the beginning of the filling portion, can end atthe end of the filling portion, and/or can be centered on the middle ofthe filling portion.

A retrofit controller can be programmed with a maximum programmedretrofit safe pressure setting that is 80-120% of the maximum retrofitinjection pressure, or any integer value for percentage in that range,or any range formed by any of those integer values, such as 100-110% or100-105%. The retrofit controller can be programmed to stop theinjection unit if an injection pressure of the injection molding machineexceeds the maximum programmed retrofit safe pressure setting.

Instead of (or in addition to) programming the retrofit controller witha maximum programmed retrofit safe pressure setting, the retrofittingcan include reprogramming the native controller from a maximumprogrammed original safe pressure setting to a maximum programmedrevised safe pressure setting. The maximum programmed revised safepressure setting can also be 80-120% of the maximum retrofit injectionpressure, or any integer value for percentage in that range, or anyrange formed by any of those integer values, such as 100-110% or100-105%.

If an injection molding machine has an original pressure reliefmechanism, then the retrofitting can include resetting the originalpressure relief mechanism from a maximum original safe pressure settingto a maximum revised safe pressure setting. The maximum revised safepressure setting can be 80-120% of the maximum retrofit injectionpressure, or any integer value for percentage in that range, or anyrange formed by any of those integer values, such as 100-110% or100-105%.

Instead of (or in addition to) resetting an original pressure reliefmechanism with a maximum revised safe pressure setting, the retrofittingcan include adding a retrofit pressure relief mechanism, which is set toa maximum retrofit safe pressure setting. The maximum retrofit safepressure setting can be 80-120% of the maximum retrofit injectionpressure, or any integer value for percentage in that range, or anyrange formed by any of those integer values, such as 100-110% or100-105%.

Any of the embodiments described in this Summary section can be carriedout in any way disclosed herein or known in the art, and can be usedand/or combined in any workable combination, including any alternativeembodiments.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an illustration of an exemplary original injection mold cycle,as programmed on an exemplary native controller, for controlling aninjection molding machine, according to the prior art.

FIG. 2 is an elevation cut-away view of an exemplary injection moldingmachine controlled by a native controller, according to the prior art.

FIG. 3 is an illustration of parts of the native controller of FIG. 2,according to the prior art.

FIG. 4 is a chart of injection pressures during injection of theoriginal injection mold cycle of FIG. 1, according to the prior art.

FIG. 5A is a cut-away view of a molten plastic material being injectedinto a mold cavity at high pressure, as known in the prior art, at afirst point in time.

FIG. 5B is a view of the injecting of FIG. 5A, at a second point intime.

FIG. 5C is a view of the injecting of FIG. 5A, at a third point in time.

FIG. 5D is a view of the injecting of FIG. 5A, at a fourth point intime.

FIG. 6A is a cut-away view of a molten plastic material being injectedinto a mold cavity at variable pressure, as known in the prior art, at afirst point in time.

FIG. 6B is a view of the injecting of FIG. 6A, at a second point intime.

FIG. 6C is a view of the injecting of FIG. 6A, at a third point in time.

FIG. 6D is a view of the injecting of FIG. 6A, at a fourth point intime.

FIG. 7A is a cut-away view of a molten plastic material being injectedinto a mold cavity, wherein the material is filling the cavity atsubstantially constant pressure, at a first point in time.

FIG. 7B is a view of the injecting of FIG. 7A, at a second point intime.

FIG. 7C is a view of the injecting of FIG. 7A, at a third point in time.

FIG. 7D is a view of the injecting of FIG. 7A, at a fourth point intime.

FIG. 8 is a chart of injection pressures during injection of anexemplary retrofit mold cycle, wherein during a filling portion of theinjection, the injection pressure is controlled to be constant.

FIG. 9 is a chart of injection pressures during injection of anexemplary retrofit mold cycle, wherein during a filling portion of theinjection, the injection pressure is falling, but still controlled to besubstantially constant.

FIG. 10 is a chart of injection pressures during injection of anexemplary retrofit mold cycle, wherein during a filling portion of theinjection, the injection pressure is rising, but still controlled to besubstantially constant.

FIG. 11 is a chart of injection pressures during injection of anexemplary retrofit mold cycle, wherein during a filling portion of theinjection, the injection pressure experiences a step-change, but isstill controlled to be substantially constant.

FIG. 12 is an illustration of parts of a retrofitted native controlleralong with a retrofit controller, according to embodiments ofretrofitting disclosed herein.

FIG. 13 is an elevation cut-away view of a retrofitted injection moldingmachine, which is a retrofitted version of the injection molding machineof FIG. 2, controlled by the retrofitted native controller and theretrofit controller of FIG. 12, according to embodiments of retrofittingdisclosed herein.

FIG. 14 is an illustration of a retrofit injection mold cycle, asprogrammed on the native controller and the retrofit controller of FIG.13, for controlling the retrofitted injection molding machine of FIG.13.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an illustration of an exemplary original injection mold cycle100, as programmed on an exemplary native controller, such as the nativecontroller 202 of FIGS. 2 and 3, for controlling 101 an injectionmolding machine, such as the exemplary injection molding machine 210 ofFIG. 2, according to the prior art. The original injection mold cycle100 includes an operating sequence of injecting molten plastic 110,cooling the plastic 120, opening the mold 130, ejecting the moldedobject from the mold 140, and closing the mold 150; these operations areoften performed in this order, though there may be some overlap betweencertain operations, and in various embodiments, one or more additionaloperations may be added. The injecting of the molten plastic 110includes an initial injecting portion 111, a filling portion 112, apacking portion 113, and a holding portion 114; however, in variousembodiments, injecting may include different portions. The injecting ofthe molten plastic 110 can be performed in any way known in the art,such as according to the chart of FIG. 4.

FIG. 2 is an elevation cut-away view of an exemplary injection moldingmachine 210 controlled by a native controller 202, according to theprior art. The molding machine 210 includes an injection unit 212 and aclamping unit 214. A plastic material may be introduced to the injectionunit 212 in the form of plastic pellets 216. The plastic pellets 216 maybe placed into a hopper 218, which feeds the plastic pellets 216 into aheated barrel 220 of the injection unit 212. The plastic pellets 216,after being fed into the heated barrel 220, may be driven to the end ofthe heated barrel 220 by a reciprocating screw 222. The heating of theheated barrel 220 and the compression of the plastic pellets 216 by thereciprocating screw 222 causes the plastic pellets 216 to melt, forminga molten plastic material 224. The molten plastic material is typicallyprocessed at a temperature selected within a range of about 130° C. toabout 410° C.

The reciprocating screw 222 forces the molten plastic material 224,toward a nozzle 226 to form a shot of plastic material, which will beinjected into a mold cavity 232 of a mold 228 via one or more gates 230,which direct the flow of the molten plastic material 224 to the moldcavity 232. In various embodiments, the mold 228 may be a heated mold ormay be an unheated mold. In other embodiments the nozzle 226 may beseparated from one or more gates 230 by a feed system with variousrunners (that may or may not be heated). The mold cavity 232 is formedbetween first and second mold sides 225, 227 of the mold 228 and thefirst and second mold sides 225, 227 are held together under pressure bythe clamping unit 214. The clamping unit 214 applies a clamping forceduring the molding process that is greater than the force exerted by theinjection pressure acting to separate the two mold halves 225, 227,thereby holding together the first and second mold sides 225, 227 whilethe molten plastic material 224 is injected into the mold cavity 232. Tosupport these clamping forces, the clamping unit 214 may be attached toa mold frame and a mold base.

Once the shot of molten plastic material 224 is injected into the moldcavity 232, the reciprocating screw 222 stops traveling forward. Themolten plastic material 224 takes the form of the mold cavity 232 andthe molten plastic material 224 cools inside the mold 228 until theplastic material 224 solidifies. Once the plastic material 224 hassolidified, the clamping unit 214 releases the first and second moldsides 225, 227, the first and second mold sides 225, 227 are separatedfrom one another, and the finished molded object may be ejected from themold 228. The mold 228 may include a plurality of mold cavities 232 toincrease overall production rates. The shapes of the cavities of theplurality of mold cavities may be identical, similar, or different fromeach other. (The latter may be considered a family of mold cavities).

A native controller 202 is in signal communication with the machine 210,as illustrated by a controller connection 202-c and a machine connection210-c (with intermediate portions omitted). The native controller 202 isin signal communication with a sensor 252 for measuring the moltenplastic material 224 in the nozzle 226, and with a sensor 253 formeasuring the molten plastic material 224 at an end of the mold cavity232.

In the embodiment of FIG. 2, the sensor 252 measures (directly orindirectly) one or more characteristics of the molten plastic material224 in the nozzle 226. The sensor 252 may or may not be located near,at, or in the nozzle 226. The sensor 252 may measure any characteristicsof the molten plastic material 224 that are known in the art, such aspressure, temperature, viscosity, flow rate, etc. or one or more of anyother characteristics that are indicative of any of these. The sensor252 may or may not be in direct contact with the molten plastic material224. The sensor 252 generates a signal that is transmitted to an inputof the native controller 202. If the sensor 252 is not located withinthe nozzle 226, the native controller 202 can be set, configured, and/orprogrammed with logic, commands, and/or executable program instructionsto provide appropriate correction factors to estimate or calculatevalues for the measured characteristic in the nozzle 226. In variousembodiments, two or more sensors of different types may be used in placeof the sensor 252.

In the embodiment of FIG. 2, the sensor 253 measures (directly orindirectly) one or more characteristics of the molten plastic material224 to detect its presence and/or condition in the mold cavity 232. Thesensor 252 may or may not be located near, at, or in the cavity 232. Invarious embodiments, the sensor 253 can be located at or near anend-of-fill position in the mold cavity 232. For example, the sensor 253can be located anywhere within the last 30% of the end-of-fill positionin the mold cavity 232. The sensor 253 may measure any characteristicsof the molten plastic material 224 that is known in the art, such aspressure, temperature, viscosity, flow rate, etc. or one or more of anyother characteristics that are indicative of any of these. The sensor253 may or may not be in direct contact with the molten plastic material224. The sensor 253 generates a signal that is transmitted to an inputof the native controller 202. If the sensor 252 is not located at theend-of-fill position in the mold cavity 232, the native controller 202can be set, configured, and/or programmed with logic, commands, and/orexecutable program instructions to provide appropriate correctionfactors to estimate or calculate values for the measured characteristicat the end-of-fill position. In various embodiments, two or more sensorsof different types may be used in place of the sensor 253.

The native controller 202 is also in signal communication with the screwcontrol 236. In the embodiment of FIG. 2, the native controller 202generates a signal that is transmitted from an output of the nativecontroller 202 to the screw control 236. The native controller 202 cancontrol injection pressures in the machine 210, by controlling the screwcontrol 236, which controls the rates of injection by the injection unit212. The controller 202 can command the screw control 236 to advance thescrew 222 at a rate that maintains a desired melt pressure of the moltenplastic material 224 in the nozzle 226.

This signal from the controller 202 may generally be used to control themolding process, such that variations in material viscosity, moldtemperatures, melt temperatures, and other variations influencingfilling rate, are taken into account by the controller 202. Adjustmentsmay be made by the controller 202 immediately during the molding cycle,or corrections can be made in subsequent cycles. Furthermore, severalsignals, from a number of cycles can be used as a basis for makingadjustments to the molding process by the controller 202. The controller202 may be connected to the sensor 252, and/or the sensor 253, and/orthe screw control 236 via any type of signal communication known in theart.

The injection molding machine 210 also includes a pressure reliefmechanism 245, which relieves pressure in the machine 210 if aninjection pressure of the machine 210 exceeds a maximum retrofit safepressure setting. The pressure relief mechanism 245 is located near thenozzle 226, but can be located at various convenient locations on themachine.

FIG. 3 is an illustration of parts of the native controller 202 of FIG.2, according to the prior art. The native controller 202 includeshardware 202-h, software 202-s, inputs 202-i, outputs 202-o, and aconnection 202-c. The hardware 202-h includes memory that stores thesoftware 202-s and one or more processors that execute the software202-s. The software 202-s includes logic, commands, and/or executableprogram instructions, including logic, commands, and/or executableprogram instructions for controlling an injection molding machineaccording to an original mold cycle. The software 202-s includes amaximum programmed retrofit safe pressure, according to embodimentsdescribed herein. The software 202-s may or may not include an operatingsystem, operating environment, application environment, and/or userinterface. The hardware 202-h uses the inputs 202-i to receive signals,data, and/or information from the injection molding machine beingcontrolled by the native controller 202. The hardware 202-h uses theoutputs 202-o to send signals, data, and/or information to the injectionmolding machine. The connection 202-c represents a pathway through whichsignals, data, and/or information can be transmitted between the nativecontroller 202 and its injection molding machine. In various embodimentsthis pathway may be a physical connection or a non-physicalcommunication link that works analogous to a physical connection, director indirect, configured in any way described herein or known in the art.In various embodiments, a native controller can be configured in anyadditional or alternate way known in the art.

FIG. 4 is a chart of injection pressures 400 during plastic injection ofthe original injection mold cycle 100 of FIG. 1, according to the priorart. The chart illustrates injection pressure (measured in the nozzle)on the vertical axis and time on the horizontal axis. The chart showshow the injection pressure changes over time, in the mold cycle, whencontrolled by a native controller, such as the native controller 202 ofFIGS. 2 and 3. The chart also shows the following portions of theoriginal mold cycle: initial injecting 410, filling 420, packing 430,and holding 440. The initial injecting 410 begins with the start of theinjection, shows a rapid increase in injection pressure, and ends oncethe rapid increase in pressure (including any overshoot/undershoot) hascompleted. In FIG. 4, the initial injecting 410 includes a maximumoriginal injection pressure 400-m. The filling 420 begins immediatelyafter the initial injecting 410, shows a relatively high injectionpressure, and ends once the mold cavity/cavities is/are volumetricallyfilled with molten plastic. The packing 430 begins immediately after thefilling 420, shows a gradually decreasing injection pressure, and endsonce the mold cavity/cavities have taken the proper mass of plastic. Theholding 440 begins immediately after the packing 430, shows a relativelylow pressure, and ends once the mold is depressurized, usually by or atthe step of opening the mold. In various embodiments, injectionpressures of an original mold cycle can be configured in any additionalor alternate way known in the art.

FIGS. 5A-5D illustrate cut-away views of a molten plastic material 524being injected into a mold cavity 532 at high pressure, such that a flow537 of the plastic material 524 experiences “jetting” as known in theprior art. FIG. 5A is a view at a first point in time; FIG. 5B is a viewat a second point in time; FIG. 5C is a view at a third point in time;and FIG. 5D is a view of at a fourth point in time. As shown in FIGS.5A-5D, during injection the flow 537 initially travels through thecavity 532 while having little to no contact with walls of the cavity532 (FIG. 5A) until the flow 537 reaches the back of the cavity 532(FIG. 5B) and then fills it (FIGS. 5C and 5D). Since jetting providespoor contact between the flow of molten plastic and the surface of themold cavity, jetting can lead to rougher and less consistent filling,which can contribute to poor quality for the molded object. Poor contactcan lead to poor heat-transfer between the molten plastic and the mold,which can result in slower cooling. Slower cooling can lead to slowermold cycle times and thus, less throughput for the machine. Thus,injecting molding by injecting at high pressures, which can causejetting, is undesirable.

FIGS. 6A-6D illustrate cut-away views of a molten plastic material 624being injected into a mold cavity 632 at variable pressure, such that aflow 637 of the plastic material 624 is in the form of droplets and/orglobules of molten plastic that are essentially sprayed into the cavity632, as known in the prior art. FIG. 6A is a view at a first point intime; FIG. 6B is a view at a second point in time; FIG. 6C is a view ata third point in time; and FIG. 6D is a view of at a fourth point intime. As shown in FIGS. 6A-6D, during injection the flow 637 initiallytravels through the cavity 632 while having little to no contact withwalls of the cavity 632 (FIGS. 6A and 6B) until the flow 637 reaches theback of the cavity and begins to accumulate on the walls of the cavity(FIG. 6C), finally filling it (FIG. 6D). Since spraying droplets and/orglobules provides poor contact between the flow of molten plastic andthe surface of the mold cavity, spraying can lead to rougher and lessconsistent filling, which can contribute to poor quality for the moldedobject. Poor contact can lead to poor heat-transfer between the moltenplastic and the mold, which can result in slower cooling. Slower coolingcan lead to slower mold cycle times and thus, less throughput for themachine. Thus, injecting molding by injecting at variable pressures,which can cause spraying of the molten plastic, is undesirable.

FIGS. 7A-7D illustrate cut-away views of a molten plastic material 724being injected into a mold cavity 732 at relatively lower, substantiallyconstant pressure, such that a flow 737 of the plastic material 724experiences a substantially unbroken, continuously advancing melt front.FIG. 7A is a view at a first point in time; FIG. 7B is a view at asecond point in time; FIG. 7C is a view at a third point in time; andFIG. 7D is a view of at a fourth point in time. As shown in FIGS. 7A-7D,during injection the flow 737 progresses through the cavity 732 whilehaving substantial contact with walls of the cavity 532 from the frontof the cavity 732 to the back of the cavity 732 throughout the filling.

As discussed above, operating at substantially constant pressuresprovides better melt flow through the mold cavity and better contactbetween the molten plastic and the surface of the mold cavity. Bettermelt flow can lead to smoother and more consistent filling, whichimproves the quality of the molded object. Better contact can lead tobetter heat-transfer between the molten plastic and the mold. Betterheat transfer can ensure that plastic remains molten throughout thefilling (avoiding ‘freeze-off’ problems). Better heat transfer can alsoprovide faster cooling. Faster cooling can lead to faster mold cycletimes and thus, greater throughput for the machine. Thus, injectingmolding by injecting at relatively lower, substantially constantpressures, which can cause this kind of melt flow, is desirable.

FIGS. 8-11 are exemplary charts of injection pressures during injectionof retrofit mold cycles.

FIG. 8 is a chart of injection pressures 800 during injection of anexemplary retrofit mold cycle, such as the retrofit mold cycle 1400 ofFIG. 14, wherein during a filling portion 860 of the injection, theinjection pressure is controlled to be at least substantially constant.The chart illustrates injection pressure (measured in the nozzle) on thevertical axis and time on the horizontal axis. The chart shows how theinjection pressure changes over time, in the retrofit mold cycle, whencontrolled by a retrofit controller, such as the retrofit controller1202 of FIG. 12. The chart also shows three portions of the retrofitmold cycle: initial injecting 850, the filling 860, and decreasingpressure 870. The initial injecting 850 begins with the start of theinjection, includes a rapid increase in injection pressure, and endsonce the rapid increase in pressure (including any overshoot/undershoot)has completed. The filling 860 begins immediately after the initialinjecting 850 and includes a relatively lower (with respect to anoriginal mold cycle), constant injection pressure. During the filling860, a retrofit controller controls the injection pressure with respectto a retrofit target injection pressure 800-t, as described herein. Invarious embodiments, during at least part (e.g. 50-100%) of the filling860, the injection pressure varies by less than a retrofit percentage(e.g. +/−0-30%) shown on the chart as ΔP, with respect to the retrofittarget injection pressure 800-t. In FIG. 8, the filling 860 includes amaximum retrofit injection pressure 800-m, which corresponds with theretrofit target injection pressure 800-t, and is located throughout thefilling portion 860. The maximum retrofit injection pressure 800-m canbe less than (e.g. 10-60% less than) an original maximum originalinjection pressure, for an original mold cycle, as described herein. Thefilling 860 continues until the mold cavity/cavities is/aresubstantially volumetrically filled (e.g. 70-100% filled) with moltenplastic, and ends once the decreasing pressure 870 portion begins. Invarious embodiments, the filling can continue until the The decreasingpressure 870 begins immediately after the filling 860, includes arapidly decreasing injection pressure, and ends once the mold isdepressurized, usually by or at the step of opening the mold. In variousembodiments, injection pressures of the retrofit mold cycle shown inFIG. 8 can be configured in any way described herein.

FIG. 9 is a chart of injection pressures 900 during injection of anexemplary retrofit mold cycle, such as the retrofit mold cycle 1400 ofFIG. 14, wherein during a filling portion 960 of the injection, theinjection pressure is decreasing, but still controlled to besubstantially constant. The chart illustrates injection pressure(measured in the nozzle) on the vertical axis and time on the horizontalaxis. The chart shows how the injection pressure changes over time, inthe retrofit mold cycle, when controlled by a retrofit controller, suchas the retrofit controller 1202 of FIG. 12. The chart also shows threeportions of the retrofit mold cycle: initial injecting 950, the filling960, and decreasing pressure 970. The initial injecting 950 begins withthe start of the injection, includes a rapid increase in injectionpressure, and ends once the rapid increase in pressure (including anyovershoot/undershoot) has completed. The filling 960 begins immediatelyafter the initial injecting 950 and includes a relatively low (withrespect to an original mold cycle), gradually falling injection pressurethat is still substantially constant. During the filling 960, a retrofitcontroller controls the injection pressure with respect to a retrofittarget injection pressure 900-t, as described herein. In variousembodiments, during at least part (e.g. 50-100%) of the filling 960, theinjection pressure varies by less than a retrofit percentage (e.g.+/−0-30%) with a 30% decrease variation shown on the chart as ΔP, withrespect to the retrofit target injection pressure 900-t. In FIG. 9, thefilling 960 includes a maximum retrofit injection pressure 900-m, whichcorresponds with the retrofit target injection pressure 900-t, and islocated at the beginning of the filling portion 960. The maximumretrofit injection pressure 900-m can be less than (e.g. 10-60% lessthan) an original maximum original injection pressure, for an originalmold cycle, as described herein. The filling 960 continues until themold cavity/cavities is/are substantially volumetrically filled (e.g.70-100% filled) with molten plastic, and ends once the decreasingpressure 870 portion begins. The decreasing pressure 970 beginsimmediately after the filling 960, includes a rapidly decreasinginjection pressure, and ends once the mold is depressurized, usually byor at the step of opening the mold. In various embodiments, injectionpressures of the retrofit mold cycle shown in FIG. 9 can be configuredin any way described herein.

FIG. 10 is a chart of injection pressures 1000 during injection of anexemplary retrofit mold cycle, such as the retrofit mold cycle 1400 ofFIG. 14, wherein during a filling portion 1060 of the injection, theinjection pressure is increasing, but still controlled to besubstantially constant. The chart illustrates injection pressure(measured in the nozzle) on the vertical axis and time on the horizontalaxis. The chart shows how the injection pressure changes over time, inthe retrofit mold cycle, when controlled by a retrofit controller, suchas the retrofit controller 1202 of FIG. 12. The chart also shows threeportions of the retrofit mold cycle: initial injecting 1050, the filling1060, and decreasing pressure 1070. The initial injecting 1050 beginswith the start of the injection, includes a rapid increase in injectionpressure, and ends once the rapid increase in pressure (including anyovershoot/undershoot) has completed. The filling 1060 begins immediatelyafter the initial injecting 1050, and includes a relatively low (withrespect to an original mold cycle), gradually rising injection pressurethat is still substantially constant. During the filling 1060, aretrofit controller controls the injection pressure with respect to aretrofit target injection pressure 1000-t, as described herein. Invarious embodiments, during at least part (e.g. 50-100%) of the filling1060, the injection pressure varies by less than a retrofit percentage(e.g. +/−0-30%) with a 30% increase variation shown on the chart as ΔP,with respect to the retrofit target injection pressure 1000-t. In FIG.10, the filling 1060 includes a maximum retrofit injection pressure1000-m, which corresponds with the retrofit target injection pressure1000-t, and is located at the end of the filling portion 1060. Themaximum retrofit injection pressure 1000-m can be less than (e.g. 10-60%less than) an original maximum original injection pressure, for anoriginal mold cycle, as described herein. The filling 1060 continuesuntil the mold cavity/cavities is/are substantially volumetricallyfilled (e.g. 70-100% filled) with molten plastic, and ends once thedecreasing pressure 1070 portion begins. The decreasing pressure 1070begins immediately after the filling 1060, includes a rapidly decreasinginjection pressure, and ends once the mold is depressurized, usually byor at the step of opening the mold. In various embodiments, injectionpressures of the retrofit mold cycle shown in FIG. 10 can be configuredin any way described herein.

FIG. 11 is a chart of injection pressures 1100 during injection of anexemplary retrofit mold cycle, such as the retrofit mold cycle 1400 ofFIG. 14, wherein during a filling portion 1160 of the injection, theinjection pressure experiences a step-change, but is still controlled tobe substantially constant. The chart illustrates injection pressure(measured in the nozzle) on the vertical axis and time on the horizontalaxis. The chart shows how the injection pressure changes over time, inthe retrofit mold cycle, when controlled by a retrofit controller, suchas the retrofit controller 1202 of FIG. 12. The chart also shows threeportions of the retrofit mold cycle: initial injecting 1150, the filling1160, which includes a first part of the filling 1160-1 and a secondpart of the filling 1160-2, and decreasing pressure 1170. The initialinjecting 1150 begins with the start of the injection, includes a rapidincrease in injection pressure, and ends once the rapid increase inpressure (including any overshoot/undershoot) has completed. The filling1160 begins immediately after the initial injecting 1150, includes thefirst part of the filling 1160-1 having a relatively low (with respectto an original mold cycle), constant injection pressure that then stepsdown 1100-s to the second part of the filling 1160-2 having an evenlower, constant injection pressure. During the filling 1160, a retrofitcontroller controls the injection pressure with respect to a retrofittarget injection pressure 1100-t, as described herein. In variousembodiments, during at least part (e.g. 50-100%) of the filling 1160,the injection pressure varies by less than a retrofit percentage (e.g.+/−0-30%) shown on the chart as ΔP, with respect to the retrofit targetinjection pressure 1100-t. In FIG. 11, the filling 1160 includes amaximum retrofit injection pressure 1100-m, which corresponds with theretrofit target injection pressure 1100-t, and is located throughout thefirst part of the filling 1160-1. The maximum retrofit injectionpressure 1100-m can be less than (e.g. 10-60% less than) an originalmaximum original injection pressure, for an original mold cycle, asdescribed herein. The filling 1160 continues until the moldcavity/cavities is/are substantially volumetrically filled with moltenplastic, and ends once the decreasing pressure 1170 portion begins. Asused herein, substantially filled means at least 70% filled and caninclude various ranges such as: 75-100%, 80-100% filled, 85-100% filled,90-100% filled, 95-100% filled, and the like. The decreasing pressure1170 begins immediately after the filling 1160, includes a rapidlydecreasing injection pressure, and ends once the mold is depressurized,usually by or at the step of opening the mold. In various embodiments,injection pressures of the retrofit mold cycle shown in FIG. 11 can beconfigured in any way described herein.

FIG. 12 is an illustration of parts of a retrofitted native controller202-r along with a retrofit controller 1202, according to embodiments ofretrofitting disclosed herein. The retrofitted native controller 202-ris the same as the native controller 202 of FIGS. 2 and 3, withlike-numbered elements configured in the same way, except as describedbelow. The retrofit controller 1202 is generally similar to the nativecontroller 202, with like-numbered elements configured in the same way,except as described below.

In the software 202-s, the maximum programmed retrofit safe pressure isreprogrammed to a maximum programmed revised safe pressure setting,according to embodiments described herein. In the retrofit controller1202, software 1202-s includes logic, commands, and/or executableprogram instructions for controlling an injection molding machineaccording to a retrofit mold cycle, such as the retrofit injection moldcycle 1400 of FIG. 14. And, the software 1202-s is programmed with amaximum programmed retrofit safe pressure setting, according toembodiments described herein.

The connection 202-c is illustrated as being in common with a connection1202-c, wherein the common connection represents a pathway through whichsignals, data, and/or information can be transmitted and/or received: a)between the retrofitted native controller 202-r and the injectionmolding machine, b) between the retrofit controller 1202 and theinjection molding machine, and c) between the retrofitted nativecontroller 202-r and the retrofit controller 1202. In variousembodiments these pathways may be physical connections or non-physicalcommunication links that work analogous to physical connections, director indirect, configured in any way described herein or known in the art.In various embodiments, a retrofitted native controller and a retrofitcontroller can be configured in any additional or alternate way known inthe art.

FIG. 12 illustrates connecting a particular output from the retrofittednative controller 202-r, which is used as a particular input to theretrofit controller 1202. In various embodiments disclosed herein, thisportion of the retrofitting includes establishing signal communicationbetween: a) an inject forward output 1202-n from outputs 202-o of theretrofitted native controller 202-r, and b) one of the inputs 1202-i ofthe retrofit controller 1202. The retrofitted native controller 202-rcan be set, configured, and/or programmed with logic, commands, and/orexecutable program instructions such that the inject forward output1202-n signals when the plastic injecting should (and/or should not)occur during a mold cycle of the molding machine. As an example, theretrofitted native controller 202-r can turn “on” the inject forwardoutput 1202-n when the plastic injecting should occur, and can turn“off” the inject forward output 1202-n when the plastic injecting shouldnot occur. The retrofit controller 1202 can use the state of the injectforward output 1202-n as a condition for injecting plastic in theretrofit mold cycle. This signal communication allows the retrofittednative controller 202-r to hand-off control of the plastic injection tothe retrofit controller 1202 for the plastic injecting portion of theretrofit mold cycle. In various embodiments, this hand-off can beaccomplished by the retrofitted native controller 202-r sending to theretrofit controller 1202 one or more additional or alternate signals,data, and/or information, which are functionally equivalent to an injectforward output, in any workable way known in the art.

FIG. 12 also illustrates moving a particular output from the retrofittednative controller 202-r to the retrofit controller 1202. In variousembodiments disclosed herein, this portion of the retrofitting includes:a) disconnecting signal communication between an injection controloutput 202-hv of the retrofitted native controller 202-r and a controlinput of an injection unit of the molding machine (signal illustrated bya phantom line), and b) establishing signal communication between aninjection control output 1202-hv of the retrofit controller 1202 and thecontrol input of the injection unit of the molding machine (signalillustrated by a solid line). The retrofit controller 1202 can be set,configured, and/or programmed with logic, commands, and/or executableprogram instructions such that the injection control output 1202-hvsignals the injection unit regarding the rate at which injecting shouldoccur during plastic injecting of a retrofit mold cycle of theretrofitted the molding machine. As an example, the retrofit controller1202 can generate the injection control output 1202-hv as an analogcontrol voltage, which scales from a particular low value (representinga minimum injection rate) to a particular high value (representing amaximum injection rate). The injection unit can use the state of theinject control output 1202-hv as the input for controlling the rate ofinjecting plastic in the retrofit mold cycle. The rate of injecting, inturn, directly affects the injection pressure of the molten plastic inthe machine. So, the injection control output 1202-hv can effectively beused to control injection pressures in the retrofitted injection moldingmachine, according to any of the embodiments disclosed herein. Thissignal communication also allows the retrofit controller 1202 to replacecontrol of the plastic injection by the retrofitted native controller202-r in the retrofit mold cycle. In various embodiments, the functionof the injection control output 1202-hv can be accomplished by theretrofit controller 1202 generating one or more additional or alternatesignals, data, and/or information, which are functionally equivalent toan injection control output and/or by sending such to one or moreadditional or alternate machine components, which partially or fullycontrol the rate of injection in the machine (and/or the effectiveinjection pressure in the machine), in any workable way known in theart. For example, in an alternative embodiment, a retrofit controllercould at least partially control injection pressures of the machine, bycontrolling a rate of melt flow through the nozzle.

In various embodiments, the retrofitting can also include rerouting thedisconnected injection control output 202-hv to one of the inputs 1202-iof the retrofit controller 1202, for use as described below.

FIG. 12 further illustrates a disable switch 1202-d, which can beprovided with the retrofitting, as described herein, and can allow auser of the retrofitted injection molding machine to select a mode ofinjection molding that disables the retrofit controller 1202, such thatthe machine and the native controller mold production versions (i.e.molded objects made using production conditions on the molding machine,wherein the objects have acceptable quality) of the plastic moldedobject according to the original mold cycle. In various embodimentsdisclosed herein, this portion of the retrofitting includes establishingsignal communication between: a) at least one user-controlled output1202-u from the disable switch 1202-d, and b) at least one of the inputs1202-i of the retrofit controller 1202. The retrofit controller 1202 canbe set, configured, and/or programmed with logic, commands, and/orexecutable program instructions such that when the user-controlledoutput 1202-u provides a particular signal, the retrofit controller 1202does not control plastic injecting during a mold cycle of the moldingmachine. As an example, when the user-controlled output 1202-u is turned“on” the injecting function of the retrofit controller 1202 is disabledand does not control the plastic injecting, and when the user-controlledoutput 1202-u is turned “off” the injecting function of the retrofitcontroller 1202 is not disabled and does control the plastic injecting.The retrofit controller 1202 can also be set, configured, and/orprogrammed with logic, commands, and/or executable program instructionssuch that when the injecting function of the retrofit controller isdisabled, the retrofit controller 1202 can receive the control output202-hv from the retrofitted native controller (as described above) andpass that received signal (in unmodified form or in modified form) tothe control input of the injection unit of the molding machine. As aresult, when the injecting function of the retrofit controller 1202 isdisabled, the retrofitted native controller 202-r can effectivelycontrol the plastic injecting (with the passed-through signal) and theretrofitted molding machine can still operate, although using anoriginal mold cycle which is likely to be relatively less efficient thenthe retrofit mold cycle. In various embodiments, the function of thedisable switch 1202-d and the user-controlled output 1202-u can beaccomplished by one or more additional or alternate user input devicesand/or signals, data, and/or information, which are functionallyequivalent, in any workable way known in the art.

FIG. 13 is an elevation view of a retrofitted injection molding machine210-r, which is a retrofitted version of the injection molding machine210 of FIG. 2, controlled by the retrofitted native controller 202-r andthe retrofit controller 1202 of FIG. 12, according to embodiments ofretrofitting disclosed herein. The retrofitted injection molding machine210-r includes a retrofitted pressure relief mechanism 245-r, which isreset from a maximum original safe pressure setting to a maximum revisedsafe pressure setting, according to embodiments described herein. Theretrofitted injection molding machine 210-r also includes an additionalretrofit pressure relief mechanism 1345, which is set to a maximumretrofit safe pressure setting, according to embodiments describedherein.

FIG. 14 is an illustration of a retrofit injection mold cycle 1400, asprogrammed on the retrofitted native controller 202-r and the retrofitcontroller 1202 of FIG. 13, for controlling the retrofitted injectionmolding machine 210-r of FIG. 13. The retrofit mold cycle 1402 includesan operating sequence of injecting molten plastic 1410, according tocontrol 1402 by the retrofit controller 1202, and then performing otherfunctions according to control 1401 by the retrofitted native controller202-r. The injecting of the molten plastic 1410 includes an initialinjecting portion 1415, a filling portion 1416, which includes using atarget pressure 1416-t, and a decreasing pressure portion 1417. Theretrofitted native controller 202-r and retrofit controller 1202 can usevarious signal communications, as described herein and known in the art,to share control of the retrofitted injection molding machine 210-rduring the retrofit mold cycle.

The injecting of the molten plastic 1410 can be partially or fullyperformed in any way described herein, for a retrofit mold cycle. Asexamples, part, parts, substantially all, or all of the initialinjecting portion 1415 can be performed according to the initialinjecting portion 850 of FIG. 8, the initial injecting portion 950 ofFIG. 9, the initial injecting portion 1050 of FIG. 10, or the initialinjecting portion 1150 of FIG. 11, or any other embodiments describedherein, including any of their alternative embodiments, and anyvariations known in the art, in any workable combination. Also asexamples, part, parts, substantially all, or all of the filling portion1416 can be performed according to the filling portion 860 of FIG. 8,the filling portion 960 of FIG. 9, the filling portion 1060 of FIG. 10,or the filling portion 1160 of FIG. 11, or any other embodimentsdescribed herein, including any of their alternative embodiments, andany variations known in the art, in any workable combination. Inparticular, the target pressure 1416-t can be selected according to anyembodiments described herein, including any alternative embodiments, andaccording to any way known in the art, in any workable combination. Asfurther examples, part, parts, substantially all, or all of thedecreasing pressure portion 1417 can be performed according to thedecreasing pressure portion 870 of FIG. 8, the decreasing pressureportion 970 of FIG. 9, the decreasing pressure portion 1070 of FIG. 10,or the decreasing pressure portion 1170 of FIG. 11, or any otherembodiments described herein, including any of their alternativeembodiments, and any variations known in the art, in any workablecombination.

The other functions include cooling the plastic 1420, opening the mold1430, ejecting the molded object from the mold 1440, and closing themold 1450, each of which is performed in the same way as thelike-numbered functions in the embodiment of FIG. 1. In some alternativeembodiments, one or more of these other functions can be modified fromits form in FIG. 1 in any way known in the art; in other alternativeembodiments, one or more of these other functions can also be partiallyor fully performed by the retrofit controller 1202.

Thus, embodiments of the present disclosure can be used to improve theoperation of a molding machine by changing its original mold cycle to aretrofit mold cycle.

A retrofit mold cycle can allow an injection molding machine to uselower injection pressures, when compared with the original mold cycle.Operating at lower pressures uses less energy, reduces stress onmechanical components, and increases the safety factor for the machine.The machine can use less energy at lower pressures since its injectionunit does not need to perform as much work. The reduced stress canlengthen the life of mechanical components and decrease the possibilityof their failure. The machine can operate at an increased safety factor,since there will be a relatively greater difference between itsoperating pressures and the maximum rated pressure for the machine.

A retrofit mold cycle can also allow an injection molding machine to usemore constant injection pressures, when compared with the original moldcycle. Operating at more constant pressures provides better melt flowthrough the mold cavity and better contact between the molten plasticand the surface of the mold cavity. Better melt flow can lead tosmoother and more consistent filling, which improves the quality of themolded object. Better contact can lead to better heat-transfer betweenthe molten plastic and the mold. Better heat transfer can ensure thatplastic remains molten throughout the filling (avoiding ‘freeze-off’problems). Better heat transfer can also provide faster cooling. Fastercooling can lead to faster mold cycle times and thus, greater throughputfor the machine.

Part, parts, or all of any of the embodiments disclosed herein can becombined with part, parts, or all of other injection molding embodimentsknown in the art, including those described below.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A method of retrofitting an injection moldingmachine, the method comprising: retrofitting an injection moldingmachine that molds production versions of plastic objects, wherein theinjection molding machine includes an injection unit, a nozzle in fluidcommunication with the injection unit, a mold in fluid communicationwith the nozzle, and a native controller that is programmed with atleast a portion of an original mold cycle for the mold, wherein theoriginal mold cycle has a maximum original injection pressure, andwherein the native controller at least partially controls injectionpressures of the machine according to the original mold cycle, whereinthe retrofitting includes: providing a retrofit controller that isprogrammed with at least a portion of a retrofit mold cycle for themold, wherein the retrofit mold cycle has a maximum retrofit injectionpressure that is 10-60% less than the maximum original injectionpressure; and establishing signal communication between an output of theretrofit controller and the injection molding machine, such that theretrofit controller at least partially controls injection pressures ofthe machine according to the retrofit mold cycle.
 2. The method of claim1, wherein the establishing includes establishing communication betweenthe retrofit controller and the injection unit.
 3. The method of claim2, wherein the retrofit controller at least partially controls injectionpressures of the machine by controlling a rate of injection by theinjection unit.
 4. The method of claim 1, wherein the retrofitcontroller at least partially controls injection pressures of themachine by controlling a rate of melt flow through the nozzle.
 5. Themethod of claim 1, wherein the establishing includes establishingcommunication between the retrofit controller and the native controller.6. The method of claim 5, wherein the establishing includes establishingcommunication between an inject forward output from the nativecontroller and an input to the retrofit controller.
 7. The method ofclaim 1, wherein the establishing includes establishing wiredcommunication.
 8. The method claim 1, wherein the providing of theretrofit controller includes providing the retrofit controller that isprogrammed with at least a portion of the retrofit mold cycle, which hasthe maximum retrofit injection pressure, and the retrofit controller isprogrammed with a maximum programmed retrofit safe pressure setting,which is 100-110% of the maximum retrofit injection pressure, and theretrofit controller is programmed to stop the injection unit if aninjection pressure of the machine exceeds the maximum programmedretrofit safe pressure setting.
 9. The method claim 1, wherein themaximum programmed retrofit safe pressure setting is 100-105% of themaximum retrofit injection pressure.
 10. The method claim 8, includingadding a retrofit pressure relief mechanism to the injection moldingmachine, wherein the retrofit pressure relief mechanism is set to amaximum retrofit safe pressure setting, which is 100-110% of the maximumretrofit injection pressure, and the pressure relief mechanism relievespressure in the machine if an injection pressure of the machine exceedsthe maximum retrofit safe pressure setting.
 11. The method claim 10,wherein the maximum retrofit safe pressure setting is 100-105% of themaximum retrofit injection pressure.
 12. The method of claim 8,including reprogramming the native controller to have a maximumprogrammed revised safe pressure setting, which is 100-110% of themaximum retrofit injection pressure.
 13. The method of claim 8, whereinthe machine has an original pressure relief mechanism, and includingsetting the original pressure relief mechanism to a maximum revised safepressure setting, which is 100-110% of the maximum retrofit injectionpressure.
 14. The method of claim 1, wherein the maximum retrofitinjection pressure is 20-60% less than the maximum original injectionpressure.
 15. The method of claim 1, wherein the maximum retrofitinjection pressure is 30-60% less than the maximum original injectionpressure.
 16. The method of claim 1, wherein the maximum retrofitinjection pressure is 40-60% less than the maximum original injectionpressure.